有限空间内低旋流流动与燃烧特性

为了对低旋流流动特性及其对火焰传播与稳定影响进行深入理解,通过实验与数值模拟相结合的方法,对有限空间内低旋流流动与燃烧特性进行研究.结果表明:改变中心孔板小孔直径,可以形成不同旋流数的旋流喷射器;在冷态条件下,随着旋流数增加,在展向平面上逐渐形成“W”形速度矢量分布;在铅垂截面内,速度矢量分布存在一个环形高速区域、中心低速区和外侧低速区.由于燃烧气体吸热膨胀、涡量诱导和温度斜压效果,使得冷态高旋回流流动转变为了燃烧条件下低旋无回流流动;在有限空间内,低旋流燃烧没有形成脱体火焰,而是形成类似于扩散燃烧火焰;随着旋流数增大,温度分布边界和化学反应边界在展向平面逐渐缩短,而在铅垂截面逐渐扩大. 

Characteristics of low swirl flow and combustion in a limited space

To further understand the characteristics of low swirl flow and its effect on the propagation and stability of flame, the characteristics of low swirl flow and combustion in a limited space were studied, through combining experiment method with numerical simulation method. Results show that,changing the diameter of the hole in the plate of center hole can form the swirl injectors with different swirl numbers;in cold state, with increasing of swirl number, gradually formed the “W” shape the velocity vector distribution on spanwise section. there are higher velocity in the annulus zone, lower velocity in central zone and lower velocity outside zone on vertical section. The absorption and heat expansion of gas, vorticity induced and temperature baroclinic effect induce a transition from high swirl flow with recirculation in cold state to low swirl flow without recirculation in combustion state; In a limited space, the low swirl combustion cannot form detached flame, but form a flame similar to the diffusion combustion flame; the temperature distribution boundary and chemical reaction boundary gradually get shorter along spanwise section, and gradually get wider along vertical section.